FIG. 1 shows an example of a conventional fuel injection apparatus, in which apparatus a flat intermediate element is provided on a fuel injection valve installed in a receiving bore of a cylinder head of an internal combustion engine. In conventional fashion, such intermediate elements are placed as bracing elements, in the form of a backing disk, on a shoulder of the receiving bore of the cylinder head. Such intermediate elements compensate for production and assembly tolerances and ensure mounting in a manner free of transverse forces even if the fuel injection valve is slightly oblique. The fuel injection apparatus is particularly suitable for use in fuel injection systems of mixture-compressing spark-ignited internal combustion engines.
Another type of simple intermediate element for a fuel injection apparatus is described in German Patent Application No. DE 101 08 466 A1. The intermediate element is a backing ring having a circular cross section, which is disposed in a region in which both the fuel injection valve and the wall of the receiving bore in the cylinder head proceed frustoconically, and serves as a compensating element for mounting and supporting the fuel injection valve.
More complex intermediate elements for fuel injection apparatuses, requiring appreciably more outlay for manufacture, are also known inter alia from German Patent Application Nos. DE 100 27 662 A1, DE 100 38 763 A1, and, European Patent No. EP 1 223 337 A1. These intermediate elements are notable for the fact that they are all constructed in multi-part or multiple-ply fashion, and are in part intended to perform sealing and damping functions. The intermediate element described in German Patent Application No. DE 100 27 662 A1 encompasses a base element and carrier element in which a sealing means is inserted, which means is penetrated by a nozzle body of the fuel injection valve. German Patent Application No. DE 100 38 763 A1 describes a multiple-ply compensating element that is made up of two stiff rings and an elastic intermediate ring disposed in sandwich fashion therebetween. This compensating element enables both tilting of the fuel injection valve with respect to the axis of the receiving bore over a relatively large angular range, and radial displacement of the fuel injection valve out of the center axis of the receiving bore.
A likewise multiple-ply intermediate element is also described in European Patent No. EP 1 223 337 A1, this intermediate element being made up of multiple backing disks that are made of a damping material. The damping material, made of metal, rubber, or PTFE, is selected and designed so as to enable acoustic damping of the vibrations and noise generated by operation of the fuel injection valve. The intermediate element must, however, encompass for that purpose four to six plies in order to achieve a desired damping effect.
In order to reduce noise emissions, U.S. Pat. No. 6,009,856 A furthermore proposes to surround the fuel injection valve with a sleeve and to fill up the resulting interstice with an elastic, acoustically damping compound. This type of acoustic damping is, however, very complex, difficult to assemble, and costly.
Also, as described in German Patent Application Nos. DE 10 2006 009 094 A1 and DE 10 2008 048 173 A1, decoupling or damping elements for fuel injection apparatuses are notable for the fact that they are embodied in multiple parts, an inner metal cushion being present as a braided, knitted, or woven wire element encapsulated in outer rings. An inner ring of the decoupling or damping element always comes into abutment against the fuel injection valve, while an outer ring of the decoupling or damping element abuts against a shoulder of a receiving bore of the cylinder head. The outer and inner ring are each simple sheet-metal rings, rectangular in cross section, having an L-shaped profile.